Try this site for medical English:
There are four catagories : doctors, nurses, pharmacists and general medical staff.
I used it for some time with doctors, they use real English speakers for the dialogues and they are done in cartoon form. Real good - there is also a resource centre for each dialogue with various exercises: matching, collocations, gap filling, document gap filling, word order and hangman.
Hope you like it as much as I do.